Unloading device for compressors.



W. F. TRBIBER.

UNLOADING DEVICE FOR GOMPRBSSORS.

APPLIUATION FILED MAY 16,1912.

1993,2999 Patented Apr. 14, 1914.

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Am 1 9 l 4 1 R p A d 6 t H m a P W. P. TRBIBBR. UNLOADING DEVICE FOR GOMPRESSORS. APPLICATION FILED MAY 16,1912.

W. P. TREIBER. UNLOADING DEVICE FOR GOMPRBSSORS.

I I APPLICATION FILED MAY 16,1912.

1,C)93,299o Patented Apr. 14, 1914.

3 SHEETS-SHEET 3.

I I "a WTLLIAM F. TREIBER, 0F CORNING, NEW YORK, ASSIGNOR TO INGERSOLL-RAND COMPANY, OF NEW YORK, N. Y., A CORPORATION OFNEW JERSEY.

UNLOADING DEVICE FOR GOMPRESSORS.

Specification of Letters Patent. Patented App 14, 19141 Application filed May 16,

1912. Serial No. seams.

To all whom. it may concern Beit known that I, WILLIAM F. .TREIBER, a citizen of the United States, residing in Corning, in the State of New York, have invented certain new and useful Improvements in Unloadin Devices for Compressors, of which the 0 lowing is a specification.

This invention relates to unloading devices for air or gas compressors and more particularly to the type of unloaders which are used in connection with constantly operating compressors for reducing the load on the compressor whenthe pressure. in the receiver or discharge line reaches a certain predetermined amount.-

In compressors as heretofore used this re-' duction of the load has been generally accomplished by closing the intake of the compressor thus causing the compressor piston or pistons to operate in a medium of a more or less reduced pressure. This has the effect of reducing the load to possibly one-third of the full load in practical operation and can not be carried much lower than this without excessive precautions against leakage.

The object of the present invention is to provide a practical means whereby the load in the compressor can be reduced below the practical limits of such an unloader as above described and this has been accomplished by providing an automatic means, operating in connection with an intake closing. controller, for unloading-the discharge line of the compressor to atmosphere.

A practical embodiment of my invention ishshfiwn in the accompanying drawings in 7 1C Figure 1 is a side elevation of a compressor and a receiver, and an unloading de- P p 6 runs to a water and dirt collector 7 of. ordinary construction which forms no part of the present invention. From the water and dirt collector 7 two small pipes 8 and 9 lead to an auxiliary valve 10 the details ber 11 in the auxiliary valve 10 admitting receiver pressure to the surface of the diaphragm 12 which, at a pressure predetermined by the tension of the spring 13, uncovers the opening of passage 14 and allows fluid at receiver pressure to enter the cham ber 15 forcing over the diaphragm 16 and the valve 17 connected therewith and opening communication from the pipe 8, containing fluid at receiver pressure, to the pipe 18. When the valve 17 is in its normal position pipe 18 is in communication with a passage 17 a which leads either to atmosphere, in an air compressor, or in a gas compressor by a pipe '(not shown) to the compressor intake.

The pipe 18 leads to the lower side of the piston 19 moving in the cylinder 20. The head of the piston 19 is provided with a valve disk 21 which is adapted to be forced by fluid pressure back ofpiston 19 against the valve seat 22 closing the inlet pipe 3 of the'compressor. The pipe 18 leads also to a discharge line unloader 23 which is of novel construction. This discharge line unloaderconsists of a casing 24: which is divided into three chambers 25, 26 and 27. Chamber 25 is in free communication with the receiver 5 through the pipe 28, chamber 26 is in free communication with the discharge pipe 4 from the compressor, and chamber 27 is in free communication with the atmosphere through the opening 29.

Seating in the partition between the chambers 25 and 26 are twin valves 30 and 31 which control the passage of the compressed fiuid from the compressor to the receiver. The bodies of these valves are hollow and form cylinders which slide on stationary piston plugs 32 and 33 threaded into the casing, these piston plugs being provided with inlet passages 34 and 35 leading to the heads of the pistons and communicating with pipe 18 through 36' and 37. "Light springs 38 and 39 are provided to .exert'a small pressure on the valves 30 and 31 tending to close them. These valves are in the nature of check valves in that of which likewise form no part of the present invention. Pipe 9 leads to a chamwhen closedthey prevent the return of fluid from the receiver into the discharge line, and seat in such a position that when seated they are held closed by the pressure in the receiver.- It is evident that a simple check valve could be used here, but such a valve, though operative offers a certain resistance to the passage of the fluid under normal running conditions, while the present valve remains open under such conditions only becoming a check valve when required.

Seated in bushings 40 and 41 in the partition between the chambers 26 and 27 and opening inwardly into the chamber 27 are twin discharge valves 42 and 43. Shanks 44 and 45eztend-upwardly from the valve 42 and are provided, at their upper end, with nuts-46 and 47 against which press springs 48 and 49 tending to hold the valves 42 and 43 in closed position. Sliding i-n cylinders 50 and 51 are pistons 52 and 53 which are cup shaped and have on their interior surfaces projecting lugs 54 and 55 which contact with the ends of the valve shanks 44 and 45. The cylinders 50 and 51 are in communication with the pipe 18 g through the pipes 56 and 57.

As stated above the chamber 27 is in communication with the atmosphere through the opening 29. If the gas being compressed is other than air a pipe (not shown) connects the opening 29. with the inlet of the compressor.

In operation, when the pressure in the receiver reaches a point which is determined by the pressure of the spring 13 in the auxiliary valve 10, the valve 17 is thrown, opening the pipe 18 to receiver pressure, the air or gas under pressure passing through the pipe 18 and pipes 36 and 37 to the interiorof the valves 30 and 31 balancing the discharge line pressure on the faces of the valves and allowing the springs 38' and 39 to force. them to a closed position. Under ordinary running conditions the pipe 18 and consequently the interior of the valves 30 and 31 are in communication with the atmosphere and the pressure in the discharge line acting against the faces of these valves, holds them in a fully open position, overcoming the pressure of the springs 38 and 39. Simultaneously with the passage of the air or gas into the valves 30 and 31 closlng them, air or gas flows into thecylinders 50 and 51 forcing up the pistons 52 and 53 and consequently raising the valves 42 and 43 establishes free communication between chambers 26 and 27 thus allowing air or gas coming from the outlet of the compressor to be discharged either to the atmosphere through the pipe 29, when air is being pumped or to the inlet of the compressor if gas is being compressed. At the same time air or gas under pressure in the pipe 18 flows into the back of the cylinder '20 raising the piston 19 and forcing the valve disk 21 therein against its seat 22 thus closing off the intake of the compressor. When the pressure in the receiver falls again below the pressure for which the auxiliary valve 10 is set the valve 17 therein will return it to its original position allowing the air or gas under pressure in the pipe 18 and conse uently that air or gas in the valves 30 an 31, tending to hold. them closedand in the cylinders 50 and 51 holding the valves 42 and 43 open and in cylinder 20 holding the valve 21 closed, willbe released and escape through the passage.17 either to atmosphere in the case of air or to the compressor intake in the case of gas.

It will be readily understood that by the use of my unloading system the load in the compressor can be reduced to a very small percentage of the full load enabling the compressor to be run with very little power when unloaded thus saving a considerable amount of power otherwise wasted,.when the compressor is run under no load for any length of time. As stated above when the compressor is unloaded only by choking the intake, the considerable amount of air or gas which is impossible, from a practical point of view, to prevent being passed through.

the compressor, must be forced into the discharge line of the compressor against the back pressure of the receiver. By applying howevera system of valves which open the discharge line to atmospheric pressure at the same time the intake is closed, the only work done by the compressor is expended in forcing a small amount of air or gas which leaks in through the intake or other openings in the compressor through the compressor and out again to a medium at atmospheric pressure. As a result great economy of power can be secured without resorting to precautions against leakage, etc., which are impracticable from a commercial point of view.

Although in the drawings a single auxiliary valve is shown controlling both the intake unloader and the discharge line unloader it is evident that a separate auxiliary valve could be used for operating each unloader as the function of this valve is merely to allow the passage of air or gas to the unloaders at a definite and predetermined point of receiver pressure. It would also be possible without invention to devise other methods of operating the two unloaders simultaneously or serially when the predetermined receiver pressure is reached and such modifications are considered to be within the spirit and scope of the invention as expressed in the claims as are also modifications in the form of the specific means shown.

What I claimis:

1. In combination, a fluid compressor, a

receiver, a discharge line connecting said compressor and said receiver, a valve for closing the intake of the compressor, an unloader in'said discharge line comprising check valve mechanism and a discharge valve-between said check valve mechanism and said compressor, pistons operatin said intake closing valve and said disc arge valve, cylinders for said pistons and auxiliary valve mechanism for connecting said cylinders with fluid under pressure when the receiver pressure reaches a predetermined amount, and with fluid at atmospheric pressure when the receiver pressure falls below a predetermined amount.

2. In combination, a fluid compressor, a

receiver, a discharge line connecting said compressor and said receiver, an unloader in said discharge line comprising a line closing valve, a discharge-valve, means for positively closing the line closing'valve by means of fluid pressure, and means for opening the discharge valve to unload the compressor outlet to atmospheric pressure by fluid pressure,'and auxiliary valve mechanism to supply fluid pressure to operate said line closing body sliding thereon, a fluid inlet passage I through said piston plug, a discharge valve, a stem on said valve, a plston engaging said stem, a cylinder for said plston and means for admitting fluid under pressure to said inlet passage and said discharge valve cylinder. v

4. In an unloading device for compressors, a discharge line unloader comprising a line closing valve, means including a cylinder and piston for positively closing said line closing valve, a discharge valve, means for operating said discharge valve including a cylinder and piston and means for supplying fluid to said cylinders to operate said valves.

. WILLIAM F. TREIBER. Witnesses:

HERBERT L. HOLLISTER, CHARLES E. DRAKE. 

